config: consolidate `*config/Config` and `*dot/Config`

## Task summary

- we currently have two configuration types defined in gossamer, first is `*config/config.go` which is used to unmarshal the toml config file, and the second is `*dot/Config` which is used to create the internal node services
- consolidate these two types into 1, this will require toml custom unmarshalling for some fields as the types don't match, eg `LogLvl`, `Pruning`, `DiscoveryInterval`